1. Field of the Invention
The present invention relates to a control valve and more particularly to a control valve with an improved valve mechanism that includes a new valve member and seating member arrangement.
2. Description of the Prior Art
U.S. Pat. No. 2,684,688, entitled Automatic Valve and System, issued to Homer G. Thornhill on July 27, 1954, teaches a valve that includes a valve body having a threaded inlet adapted to be connected to a side arm of a Christmas tree manifold. The valve body also has a flanged outlet adapted to be connected to a positive choke from which leads the pipe line going to the storage tank. The valve body is in the shape of a T, the inlet being at the base of the T, and the outlet being in one of the arms of the T. Through the other arm of the T projects a valve stem on which is mounted the valve which cooperates with a removable valve seat threadedly supported within the outlet. The valve stem is slidably supported within the center of the arm of the T opposite the outlet by means of a flanged valve bonnet. The valve bonnet is sealed to the end of the valve body by means of a ring gasket and is secured thereto by means of a fast coupling.
The valve bonnet is provided with two cylindrical bearings for supporting the cylindrical valve stem. Within each of the two annular grooves and within the bearings there is mounted a neoprene O-ring disposed between a pair of leather non-extrusion rings. These form a pair of spaced sliding seals between the valve stem and the valve bonnet.
Other patents include U.S. Pat. No. 3,166,092, U.S. Pat. No. 2,227,297, U.S. Pat. No. 2,684,689, U.S. Pat. No. 3,049,140 and U.S. Pat. No. 3,166,093. All of these patents teach valves which have valve members which are conically shaped and which are adapted to be inserted into a valve seat or sealing member. These types of valves are generally referred to as needle and seat choke valves. The interface between the surface of the valve member and the surface of the valve seat serves not only to control the flow through the valve itself, but also serves as the shutoff when the valve is closed. This interface is therefore subject to wear. Furthermore an additional purpose of the valve is to decrease pressure pressure across the controlled orifice due to fluid flow. The pressure decrease is dependent on the degree that the orifice is opened. Another problem with the valve is that its resilient seal is set by the pressure within it.